I disagree.
No, I'm not disputing the size of the virus or the porousness of the face masks. I disagree that the only benefit of face masks is stopping airborne germs.
Influenzas, colds, and lots of other disease are contagious through tiny droplets of euphemistic water. Really it's droplets of spit or snot, but water is much nicer to talk about. Lots of these water droplets are expelled when people sneeze and cough and a few when people talk and yawn. Even though these germ filled water droplets are usually so tiny they are invisible and even though they fly through the air, a disease that can be transmitted this way is not really airborne. Each droplet is a lovely wet microcosm that can sustain germs that couldn't live in plain, dry air. Droplets are big enough to hold colonies of germs that are too big and too heavy to float in the air. A truly airborne virus can float in the air like a dust mote and can exist outside of a water droplet.
Face masks don't stop airborne germs but they do stop germ filled water droplets. So either swine flu is not airborne today and face masks will stop its transmission or it is airborne and face masks will make it less contagious by stopping those germs in water droplets.
The other thing face masks do is change habits. They stop people from biting their nails and rubbing their nose. They stop people from coughing into their hand just before turning a doorknob or pushing an elevator button.
